cregit-Linux how code gets into the kernel

Release 4.15 kernel/power/swap.c

Directory: kernel/power
/*
 * linux/kernel/power/swap.c
 *
 * This file provides functions for reading the suspend image from
 * and writing it to a swap partition.
 *
 * Copyright (C) 1998,2001-2005 Pavel Machek <pavel@ucw.cz>
 * Copyright (C) 2006 Rafael J. Wysocki <rjw@sisk.pl>
 * Copyright (C) 2010-2012 Bojan Smojver <bojan@rexursive.com>
 *
 * This file is released under the GPLv2.
 *
 */


#define pr_fmt(fmt) "PM: " fmt

#include <linux/module.h>
#include <linux/file.h>
#include <linux/delay.h>
#include <linux/bitops.h>
#include <linux/genhd.h>
#include <linux/device.h>
#include <linux/bio.h>
#include <linux/blkdev.h>
#include <linux/swap.h>
#include <linux/swapops.h>
#include <linux/pm.h>
#include <linux/slab.h>
#include <linux/lzo.h>
#include <linux/vmalloc.h>
#include <linux/cpumask.h>
#include <linux/atomic.h>
#include <linux/kthread.h>
#include <linux/crc32.h>
#include <linux/ktime.h>

#include "power.h"


#define HIBERNATE_SIG	"S1SUSPEND"

/*
 * When reading an {un,}compressed image, we may restore pages in place,
 * in which case some architectures need these pages cleaning before they
 * can be executed. We don't know which pages these may be, so clean the lot.
 */

static bool clean_pages_on_read;

static bool clean_pages_on_decompress;

/*
 *      The swap map is a data structure used for keeping track of each page
 *      written to a swap partition.  It consists of many swap_map_page
 *      structures that contain each an array of MAP_PAGE_ENTRIES swap entries.
 *      These structures are stored on the swap and linked together with the
 *      help of the .next_swap member.
 *
 *      The swap map is created during suspend.  The swap map pages are
 *      allocated and populated one at a time, so we only need one memory
 *      page to set up the entire structure.
 *
 *      During resume we pick up all swap_map_page structures into a list.
 */


#define MAP_PAGE_ENTRIES	(PAGE_SIZE / sizeof(sector_t) - 1)

/*
 * Number of free pages that are not high.
 */

static inline unsigned long low_free_pages(void) { return nr_free_pages() - nr_free_highpages(); }

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Bojan Smojver17100.00%1100.00%
Total17100.00%1100.00%

/* * Number of pages required to be kept free while writing the image. Always * half of all available low pages before the writing starts. */
static inline unsigned long reqd_free_pages(void) { return low_free_pages() / 2; }

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Bojan Smojver16100.00%1100.00%
Total16100.00%1100.00%

struct swap_map_page { sector_t entries[MAP_PAGE_ENTRIES]; sector_t next_swap; }; struct swap_map_page_list { struct swap_map_page *map; struct swap_map_page_list *next; }; /** * The swap_map_handle structure is used for handling swap in * a file-alike way */ struct swap_map_handle { struct swap_map_page *cur; struct swap_map_page_list *maps; sector_t cur_swap; sector_t first_sector; unsigned int k; unsigned long reqd_free_pages; u32 crc32; }; struct swsusp_header { char reserved[PAGE_SIZE - 20 - sizeof(sector_t) - sizeof(int) - sizeof(u32)]; u32 crc32; sector_t image; unsigned int flags; /* Flags to pass to the "boot" kernel */ char orig_sig[10]; char sig[10]; } __packed; static struct swsusp_header *swsusp_header; /** * The following functions are used for tracing the allocated * swap pages, so that they can be freed in case of an error. */ struct swsusp_extent { struct rb_node node; unsigned long start; unsigned long end; }; static struct rb_root swsusp_extents = RB_ROOT;
static int swsusp_extents_insert(unsigned long swap_offset) { struct rb_node **new = &(swsusp_extents.rb_node); struct rb_node *parent = NULL; struct swsusp_extent *ext; /* Figure out where to put the new node */ while (*new) { ext = rb_entry(*new, struct swsusp_extent, node); parent = *new; if (swap_offset < ext->start) { /* Try to merge */ if (swap_offset == ext->start - 1) { ext->start--; return 0; } new = &((*new)->rb_left); } else if (swap_offset > ext->end) { /* Try to merge */ if (swap_offset == ext->end + 1) { ext->end++; return 0; } new = &((*new)->rb_right); } else { /* It already is in the tree */ return -EINVAL; } } /* Add the new node and rebalance the tree. */ ext = kzalloc(sizeof(struct swsusp_extent), GFP_KERNEL); if (!ext) return -ENOMEM; ext->start = swap_offset; ext->end = swap_offset; rb_link_node(&ext->node, parent, new); rb_insert_color(&ext->node, &swsusp_extents); return 0; }

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Nigel Cunningham21699.54%150.00%
Davidlohr Bueso A10.46%150.00%
Total217100.00%2100.00%

/** * alloc_swapdev_block - allocate a swap page and register that it has * been allocated, so that it can be freed in case of an error. */
sector_t alloc_swapdev_block(int swap) { unsigned long offset; offset = swp_offset(get_swap_page_of_type(swap)); if (offset) { if (swsusp_extents_insert(offset)) swap_free(swp_entry(swap, offset)); else return swapdev_block(swap, offset); } return 0; }

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Nigel Cunningham5596.49%150.00%
Hugh Dickins23.51%150.00%
Total57100.00%2100.00%

/** * free_all_swap_pages - free swap pages allocated for saving image data. * It also frees the extents used to register which swap entries had been * allocated. */
void free_all_swap_pages(int swap) { struct rb_node *node; while ((node = swsusp_extents.rb_node)) { struct swsusp_extent *ext; unsigned long offset; ext = rb_entry(node, struct swsusp_extent, node); rb_erase(node, &swsusp_extents); for (offset = ext->start; offset <= ext->end; offset++) swap_free(swp_entry(swap, offset)); kfree(ext); } }

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PersonTokensPropCommitsCommitProp
Nigel Cunningham8497.67%133.33%
Hugh Dickins11.16%133.33%
Geliang Tang11.16%133.33%
Total86100.00%3100.00%


int swsusp_swap_in_use(void) { return (swsusp_extents.rb_node != NULL); }

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Nigel Cunningham16100.00%1100.00%
Total16100.00%1100.00%

/* * General things */ static unsigned short root_swap = 0xffff; static struct block_device *hib_resume_bdev; struct hib_bio_batch { atomic_t count; wait_queue_head_t wait; blk_status_t error; };
static void hib_init_batch(struct hib_bio_batch *hb) { atomic_set(&hb->count, 0); init_waitqueue_head(&hb->wait); hb->error = BLK_STS_OK; }

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Christoph Hellwig35100.00%2100.00%
Total35100.00%2100.00%


static void hib_end_io(struct bio *bio) { struct hib_bio_batch *hb = bio->bi_private; struct page *page = bio->bi_io_vec[0].bv_page; if (bio->bi_status) { pr_alert("Read-error on swap-device (%u:%u:%Lu)\n", MAJOR(bio_dev(bio)), MINOR(bio_dev(bio)), (unsigned long long)bio->bi_iter.bi_sector); } if (bio_data_dir(bio) == WRITE) put_page(page); else if (clean_pages_on_read) flush_icache_range((unsigned long)page_address(page), (unsigned long)page_address(page) + PAGE_SIZE); if (bio->bi_status && !hb->error) hb->error = bio->bi_status; if (atomic_dec_and_test(&hb->count)) wake_up(&hb->wait); bio_put(bio); }

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Christoph Hellwig12981.65%466.67%
James Morse2817.72%116.67%
Joe Perches10.63%116.67%
Total158100.00%6100.00%


static int hib_submit_io(int op, int op_flags, pgoff_t page_off, void *addr, struct hib_bio_batch *hb) { struct page *page = virt_to_page(addr); struct bio *bio; int error = 0; bio = bio_alloc(__GFP_RECLAIM | __GFP_HIGH, 1); bio->bi_iter.bi_sector = page_off * (PAGE_SIZE >> 9); bio_set_dev(bio, hib_resume_bdev); bio_set_op_attrs(bio, op, op_flags); if (bio_add_page(bio, page, PAGE_SIZE, 0) < PAGE_SIZE) { pr_err("Adding page to bio failed at %llu\n", (unsigned long long)bio->bi_iter.bi_sector); bio_put(bio); return -EFAULT; } if (hb) { bio->bi_end_io = hib_end_io; bio->bi_private = hb; atomic_inc(&hb->count); submit_bio(bio); } else { error = submit_bio_wait(bio); bio_put(bio); } return error; }

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PersonTokensPropCommitsCommitProp
Christoph Hellwig16090.91%233.33%
Michael Christie137.39%233.33%
Joe Perches21.14%116.67%
Mel Gorman10.57%116.67%
Total176100.00%6100.00%


static blk_status_t hib_wait_io(struct hib_bio_batch *hb) { wait_event(hb->wait, atomic_read(&hb->count) == 0); return blk_status_to_errno(hb->error); }

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Christoph Hellwig36100.00%2100.00%
Total36100.00%2100.00%

/* * Saving part */
static int mark_swapfiles(struct swap_map_handle *handle, unsigned int flags) { int error; hib_submit_io(REQ_OP_READ, 0, swsusp_resume_block, swsusp_header, NULL); if (!memcmp("SWAP-SPACE",swsusp_header->sig, 10) || !memcmp("SWAPSPACE2",swsusp_header->sig, 10)) { memcpy(swsusp_header->orig_sig,swsusp_header->sig, 10); memcpy(swsusp_header->sig, HIBERNATE_SIG, 10); swsusp_header->image = handle->first_sector; swsusp_header->flags = flags; if (flags & SF_CRC32_MODE) swsusp_header->crc32 = handle->crc32; error = hib_submit_io(REQ_OP_WRITE, REQ_SYNC, swsusp_resume_block, swsusp_header, NULL); } else { pr_err("Swap header not found!\n"); error = -ENODEV; } return error; }

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PersonTokensPropCommitsCommitProp
Rafael J. Wysocki9969.72%433.33%
Bojan Smojver149.86%18.33%
Jiri Slaby74.93%18.33%
Vivek Goyal64.23%18.33%
Christoph Hellwig64.23%216.67%
Michael Christie42.82%18.33%
Andrew Morton42.82%18.33%
Joe Perches21.41%18.33%
Total142100.00%12100.00%

/** * swsusp_swap_check - check if the resume device is a swap device * and get its index (if so) * * This is called before saving image */
static int swsusp_swap_check(void) { int res; res = swap_type_of(swsusp_resume_device, swsusp_resume_block, &hib_resume_bdev); if (res < 0) return res; root_swap = res; res = blkdev_get(hib_resume_bdev, FMODE_WRITE, NULL); if (res) return res; res = set_blocksize(hib_resume_bdev, PAGE_SIZE); if (res < 0) blkdev_put(hib_resume_bdev, FMODE_WRITE); /* * Update the resume device to the one actually used, * so the test_resume mode can use it in case it is * invoked from hibernate() to test the snapshot. */ swsusp_resume_device = hib_resume_bdev->bd_dev; return res; }

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Rafael J. Wysocki7182.56%555.56%
Chen Yu78.14%111.11%
Jiri Slaby44.65%111.11%
Al Viro22.33%111.11%
Tejun Heo22.33%111.11%
Total86100.00%9100.00%

/** * write_page - Write one page to given swap location. * @buf: Address we're writing. * @offset: Offset of the swap page we're writing to. * @hb: bio completion batch */
static int write_page(void *buf, sector_t offset, struct hib_bio_batch *hb) { void *src; int ret; if (!offset) return -ENOSPC; if (hb) { src = (void *)__get_free_page(__GFP_RECLAIM | __GFP_NOWARN | __GFP_NORETRY); if (src) { copy_page(src, buf); } else { ret = hib_wait_io(hb); /* Free pages */ if (ret) return ret; src = (void *)__get_free_page(__GFP_RECLAIM | __GFP_NOWARN | __GFP_NORETRY); if (src) { copy_page(src, buf); } else { WARN_ON_ONCE(1); hb = NULL; /* Go synchronous */ src = buf; } } } else { src = buf; } return hib_submit_io(REQ_OP_WRITE, REQ_SYNC, offset, src, hb); }

Contributors

PersonTokensPropCommitsCommitProp
Rafael J. Wysocki5636.84%327.27%
Bojan Smojver4932.24%218.18%
Andrew Morton3221.05%19.09%
Christoph Hellwig106.58%218.18%
Michael Christie21.32%19.09%
Mel Gorman21.32%19.09%
Jan Beulich10.66%19.09%
Total152100.00%11100.00%


static void release_swap_writer(struct swap_map_handle *handle) { if (handle->cur) free_page((unsigned long)handle->cur); handle->cur = NULL; }

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Rafael J. Wysocki2779.41%266.67%
Andrew Morton720.59%133.33%
Total34100.00%3100.00%


static int get_swap_writer(struct swap_map_handle *handle) { int ret; ret = swsusp_swap_check(); if (ret) { if (ret != -ENOSPC) pr_err("Cannot find swap device, try swapon -a\n"); return ret; } handle->cur = (struct swap_map_page *)get_zeroed_page(GFP_KERNEL); if (!handle->cur) { ret = -ENOMEM; goto err_close; } handle->cur_swap = alloc_swapdev_block(root_swap); if (!handle->cur_swap) { ret = -ENOSPC; goto err_rel; } handle->k = 0; handle->reqd_free_pages = reqd_free_pages(); handle->first_sector = handle->cur_swap; return 0; err_rel: release_swap_writer(handle); err_close: swsusp_close(FMODE_WRITE); return ret; }

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PersonTokensPropCommitsCommitProp
Jiri Slaby6647.83%222.22%
Rafael J. Wysocki5338.41%333.33%
Andrew Morton107.25%111.11%
Bojan Smojver75.07%222.22%
Joe Perches21.45%111.11%
Total138100.00%9100.00%


static int swap_write_page(struct swap_map_handle *handle, void *buf, struct hib_bio_batch *hb) { int error = 0; sector_t offset; if (!handle->cur) return -EINVAL; offset = alloc_swapdev_block(root_swap); error = write_page(buf, offset, hb); if (error) return error; handle->cur->entries[handle->k++] = offset; if (handle->k >= MAP_PAGE_ENTRIES) { offset = alloc_swapdev_block(root_swap); if (!offset) return -ENOSPC; handle->cur->next_swap = offset; error = write_page(handle->cur, handle->cur_swap, hb); if (error) goto out; clear_page(handle->cur); handle->cur_swap = offset; handle->k = 0; if (hb && low_free_pages() <= handle->reqd_free_pages) { error = hib_wait_io(hb); if (error) goto out; /* * Recalculate the number of required free pages, to * make sure we never take more than half. */ handle->reqd_free_pages = reqd_free_pages(); } } out: return error; }

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PersonTokensPropCommitsCommitProp
Rafael J. Wysocki13972.02%225.00%
Bojan Smojver3317.10%337.50%
Andrew Morton136.74%112.50%
Christoph Hellwig73.63%112.50%
Jan Beulich10.52%112.50%
Total193100.00%8100.00%


static int flush_swap_writer(struct swap_map_handle *handle) { if (handle->cur && handle->cur_swap) return write_page(handle->cur, handle->cur_swap, NULL); else return -EINVAL; }

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Rafael J. Wysocki3895.00%150.00%
Andrew Morton25.00%150.00%
Total40100.00%2100.00%


static int swap_writer_finish(struct swap_map_handle *handle, unsigned int flags, int error) { if (!error) { flush_swap_writer(handle); pr_info("S"); error = mark_swapfiles(handle, flags); pr_cont("|\n"); } if (error) free_all_swap_pages(root_swap); release_swap_writer(handle); swsusp_close(FMODE_WRITE); return error; }

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Jiri Slaby6895.77%150.00%
Joe Perches34.23%150.00%
Total71100.00%2100.00%

/* We need to remember how much compressed data we need to read. */ #define LZO_HEADER sizeof(size_t) /* Number of pages/bytes we'll compress at one time. */ #define LZO_UNC_PAGES 32 #define LZO_UNC_SIZE (LZO_UNC_PAGES * PAGE_SIZE) /* Number of pages/bytes we need for compressed data (worst case). */ #define LZO_CMP_PAGES DIV_ROUND_UP(lzo1x_worst_compress(LZO_UNC_SIZE) + \ LZO_HEADER, PAGE_SIZE) #define LZO_CMP_SIZE (LZO_CMP_PAGES * PAGE_SIZE) /* Maximum number of threads for compression/decompression. */ #define LZO_THREADS 3 /* Minimum/maximum number of pages for read buffering. */ #define LZO_MIN_RD_PAGES 1024 #define LZO_MAX_RD_PAGES 8192 /** * save_image - save the suspend image data */
static int save_image(struct swap_map_handle *handle, struct snapshot_handle *snapshot, unsigned int nr_to_write) { unsigned int m; int ret; int nr_pages; int err2; struct hib_bio_batch hb; ktime_t start; ktime_t stop; hib_init_batch(&hb); pr_info("Saving image data pages (%u pages)...\n", nr_to_write); m = nr_to_write / 10; if (!m) m = 1; nr_pages = 0; start = ktime_get(); while (1) { ret = snapshot_read_next(snapshot); if (ret <= 0) break; ret = swap_write_page(handle, data_of(*snapshot), &hb); if (ret) break; if (!(nr_pages % m)) pr_info("Image saving progress: %3d%%\n", nr_pages / m * 10); nr_pages++; } err2 = hib_wait_io(&hb); stop = ktime_get(); if (!ret) ret = err2; if (!ret) pr_info("Image saving done\n"); swsusp_show_speed(start, stop, nr_to_write, "Wrote"); return ret; }

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PersonTokensPropCommitsCommitProp
Rafael J. Wysocki10555.26%222.22%
Andrew Morton4322.63%222.22%
Jiri Slaby147.37%111.11%
Christoph Hellwig115.79%111.11%
Tina Ruchandani84.21%111.11%
Joe Perches63.16%111.11%
Bojan Smojver31.58%111.11%
Total190100.00%9100.00%

/** * Structure used for CRC32. */ struct crc_data { struct task_struct *thr; /* thread */ atomic_t ready; /* ready to start flag */ atomic_t stop; /* ready to stop flag */ unsigned run_threads; /* nr current threads */ wait_queue_head_t go; /* start crc update */ wait_queue_head_t done; /* crc update done */ u32 *crc32; /* points to handle's crc32 */ size_t *unc_len[LZO_THREADS]; /* uncompressed lengths */ unsigned char *unc[LZO_THREADS]; /* uncompressed data */ }; /** * CRC32 update function that runs in its own thread. */
static int crc32_threadfn(void *data) { struct crc_data *d = data; unsigned i; while (1) { wait_event(d->go, atomic_read(&d->ready) || kthread_should_stop()); if (kthread_should_stop()) { d->thr = NULL; atomic_set(&d->stop, 1); wake_up(&d->done); break; } atomic_set(&d->ready, 0); for (i = 0; i < d->run_threads; i++) *d->crc32 = crc32_le(*d->crc32, d->unc[i], *d->unc_len[i]); atomic_set(&d->stop, 1); wake_up(&d->done); } return 0; }

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Bojan Smojver12986.00%233.33%
Rafael J. Wysocki149.33%350.00%
Jiri Slaby74.67%116.67%
Total150100.00%6100.00%

/** * Structure used for LZO data compression. */ struct cmp_data { struct task_struct *thr; /* thread */ atomic_t ready; /* ready to start flag */ atomic_t stop; /* ready to stop flag */ int ret; /* return code */ wait_queue_head_t go; /* start compression */ wait_queue_head_t done; /* compression done */ size_t unc_len; /* uncompressed length */ size_t cmp_len; /* compressed length */ unsigned char unc[LZO_UNC_SIZE]; /* uncompressed buffer */ unsigned char cmp[LZO_CMP_SIZE]; /* compressed buffer */ unsigned char wrk[LZO1X_1_MEM_COMPRESS]; /* compression workspace */ }; /** * Compression function that runs in its own thread. */
static int lzo_compress_threadfn(void *data) { struct cmp_data *d = data; while (1) { wait_event(d->go, atomic_read(&d->ready) || kthread_should_stop()); if (kthread_should_stop()) { d->thr = NULL; d->ret = -1; atomic_set(&d->stop, 1); wake_up(&d->done); break; } atomic_set(&d->ready, 0); d->ret = lzo1x_1_compress(d->unc, d->unc_len, d->cmp + LZO_HEADER, &d->cmp_len, d->wrk); atomic_set(&d->stop, 1); wake_up(&d->done); } return 0; }

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Bojan Smojver13595.74%266.67%
Rafael J. Wysocki64.26%133.33%
Total141100.00%3100.00%

/** * save_image_lzo - Save the suspend image data compressed with LZO. * @handle: Swap map handle to use for saving the image. * @snapshot: Image to read data from. * @nr_to_write: Number of pages to save. */
static int save_image_lzo(struct swap_map_handle *handle, struct snapshot_handle *snapshot, unsigned int nr_to_write) { unsigned int m; int ret = 0; int nr_pages; int err2; struct hib_bio_batch hb; ktime_t start; ktime_t stop; size_t off; unsigned thr, run_threads, nr_threads; unsigned char *page = NULL; struct cmp_data *data = NULL; struct crc_data *crc = NULL; hib_init_batch(&hb); /* * We'll limit the number of threads for compression to limit memory * footprint. */ nr_threads = num_online_cpus() - 1; nr_threads = clamp_val(nr_threads, 1